Copper base alloy



3,297,497 COPPER BASE ALLOY George H. Eichelman, Jr., and IrwinBroverman, Cheshire, Conn., assignors to Olin Mathieson ChemicalCorporation, a corporation of Virginia No Drawing. Filed Jan. 29, 1964,Ser. No. 341,121 8 Claims. (Cl. 14832.5)

The present invention relates to improved aluminumbronze alloys and tothe preparation thereof. More particularly, the present inventionresides in novel and inexpensively prepared copper base alloyscontaining from 9.0 to 11.8 percent aluminum, from 0.05 to 5.0 percentof at least one additional element having a solid solubility in copperof less than 4.0 percent and which forms one or more intermetalliccompounds with aluminum, with the total quantity of said additionalelements being less than 10.0 percent and preferably less than 5.0percent, and the balance essentially copper. The additional element ispreferably one or more of the following elements: iron; chromium;titanium; zirconium; molybdenum; columbium; and vanadium. The foregoingalloys are prepared in such a manner as to be characterized by physicalproperties heretofore unattainable in alloys of this type. For example,the novel alloys of the present invention attain surprisingly hightensile strengths combined with high ductility. This combination ofproperties provides superior toughness and formability. In addition, thenovel alloys of the present invention have reasonably good electricalconductivity plus good brazability, solderability, Weldability,corrosion resistance, stress corrosion resistance, and fatigue strength.

I The novel and inexpensively prepared alloys of the present inventionreadily attain a combination of strength and ductility heretoforeunattainable in these alloys, for example, tensile strengths rangingfrom 120,000 to 160,000 p.s.i. and yield strengths ranging from 60,000to 80,000 p.s.i. at 0.2 percent offset in combination with elongationsranging from 12 to 9 percent. In addition, electrical conductivityvalues ranging from 10 to 16 percent IACS are attained. Properties ofthis type approximate those provided by the relatively expensiveberyllium-copper alloys. A lower cost of series of alloys exhibitingproperties similar to the reltaively expensive beryllium-copper alloys,such as provided in accordance with the present invention, wouldtherefore, find wide application in a Wide variety of fields, as areplacement for beryllium-copper in the manufacture of electricalsprings, contacts, and diaphragms. In fact, considerable effort has beenexpended in the art, heretofore unsuccessful, to develop such a lowercost substitute for beryllium-copper.

Alloys exhibiting the foregoing properties would also tend to replacelower cost copper base alloys having lower strengths. In addition, thesealloys would tend to replace a variety of other copper base alloys whichare in a lower price range than beryllium-copper, e.g., Phosphor-bronze.

The alloys of the present invention are extremely versatile and have awide variety of other uses exemplificative of which are: corrosionresistant parts, such as condenser tubes and valves; metal bellows; heatresistant parts in which resistance to corrosion at high temperature isrequired, such as parts for internal combustion engines; wear resistantparts; and metal forming dies.

Accordingly, it is an object of the present invention to provide new andimproved aluminum-bronze alloys and methods for the preparation thereof.

It is a further object of the present invention to provide an alloy asaforesaid which is characterized by physical properties heretoforeunattainable in alloys of this type, and especially possessing a greatlyimproved combination of yield strength, tensile strength and ductility.

It is a still further object of the present invention to provide analloy as aforesaid which attains these greatly improved physicalproperties without degradation of other properties so desirable inalloys of this type.

It is a still further object of the present invention to provide analloy and process as above conveniently, expenditiously and atreasonable cost.

Further objects and advantages of the present invention will appearhereinafter.

In accordance with the present invention it has noW been found that theforegoing objects and advantages of the present invention may be readilyaccomplished. The process of the present invention comprises: hotworking at a temperature of from -1850 F. to 1000 F. a copper base alloycontaining from 9.0 to 11.8 percent aluminum, from 0.05 to 5.0 percentof at least one additional element having a solid solubility in copperof less than 4.0 percent and which forms at least one intermetalliccompound with aluminum, with the total quantity of said additionalelements added being less than 10.0 percent and preferably less than 5.0percent, and the balance essentially copper; and cold Working said alloyat a temperature below 500 F.

In the improved aluminum-bronze alloy of the present invention, theadditional element referred to above which has a solid solubility incopper of less than 4.0 percent and which forms one or moreintermetallic compounds with aluminum, is preferably selected from thegroup consisting of the following elements in the following preferredamounts: iron from 2.0 to 5.0 percent; chromium from 0.4 to 2.0 percent;titanium from 0.4 to 2.0 percent; zirconium from 0.05 to 0.2 percent;molybdenum from 0.4 to 2.0 percent; columbium from 0.4 to 2.0 percent;vanadium from 0.4 to 2.0 percent; and mixtures thereof. In addition, theimproved alloy of the present invention has a metallographic structurecontaining from 5 to percent beta phase and the remainder alpha phase.The micro-structure of the present alloy contains a dispersion whichlikely consists in part of one or more intermetallic compounds which isformed between aluminum and each of the additional elements of thepresent invention. The present alloy also has a uniformly finemetallographic grain structure with a grain size less than 0.065 mm. andgenerally less than 0.040 mm.

In co-pending application Serial No. 328,184, filed December 5, 1963 byGeorge H. Eichelman Jr., and Irwin Broverman, there is described a novelaluminum-bronze alloy containing from 9.0 to 11.8 percent aluminum andthe balance essentially copper. The improved alloy of said co-pendingapplication has a metallographic structure containing from 5 to 95percent beta phase and remainder alpha phase. In addition, the alloy ofsaid copending application has a uniformly fine metallographic grainstructure with a grain size less than 0.065 mm. The alloys of saidco-pending application readily attain a combination of strength andductility heretofore unattainable in alloys of this type.

The improved alloys of the present invention represent a still furtherimprovement over the alloys of said co-pending application. Thisimprovement is attained by the addition of from 0.05 to 5.0 percent ofat least one additional element having a solid solubility in copper ofless than 4.0 percent and which forms at least one interrnetalliccompound with aluminium. The additional element is preferably selectedfrom the following group of elements, although the present invention isnot necessarily limited to these elements, iron, chromium, titanium,zirconium, molybdenum, columbium, vanadium and mixtures thereof in thepreferred amounts set forth hereinabove. The additional element orelements serve to inhibit the grain growth so that it is possible toobtain a still finer grain size than is attained in accordance with theteaching of said co-pending application. This further improvement ingrain size is due to the formation of the abovementioned dispersion,including the intermetallic compound or compounds. The overall effect isto develop even higher strength levels in the present alloys than isattained in accordance with the teaching of said co-pending applicationfor comparable ductilities.

The alloys of the present invention contain from 9.0 to 11.8 percentaluminum. The aluminum content must critically 'be within theaforementioned range and preferably is within the more limited range 9.4to 10.4 percent aluminum and optimally is between 9.8 to 10.0 percentaluminum. In addition, the alloy of the present invention mustcritically contain from 0.05 to 5.0 percent of at least one additionalelement as defined above, with the following being preferred: iron;chromium; titanium; zirconium; molybdenum; columbium; and vanadium. Ironis preferably present in an amount of from 2 to percent and optimallyfrom 3 to 4 percent. Chromium, titanium, molybdenum, columbium, andvanadium are each preferably present in an amount of from 0.4 to 2.0percent, and optimally in an amount of from 1 to 2 percent. Zirconium ispreferably present in an amount of from 0.05 to 0.2 percent andoptimally from 0.1 to 0.2 percent.

The additional element must, as discussed above, have limited solidsolubility in copper and be an intermetallic compound former withaluminum. Preferably, the additional element should be a strongintermetallic compound former with aluminum and should in factpreferentially form intermetallic compounds with aluminum. In addition,the additional element and/or intermetallic compounds formed shouldpreferably form a dispersion in copper with limited solid solubility attemperatures up to 1800 F. The presence of this dispersion acts toprevent grain growth at high heat treatment temperatures.

The remainder or balance of the alloy is essentially copper, i.e., thealloy may contain incidental impurities or other materials which do notmaterially degrade the physical characteristics of the alloy. Examplesof such elements which can be present include tin, zinc, lead, nickel,silicon, silver, phosphorus, magnesuim, antimony, bismuth, and arsenic.

The alloy of the present invention is prepared in accordance with theforegoing critical combination of steps to provide the surprisinglyimproved composition of the present invention.

The first critical step in the process of the present invention is thehot working step in the aforementioned critical temperature range.Preparatory to the hot working step the alloy may naturally be meltedand cast in a suitable 'bar or ingot form using conventional practicesto insure compositional and structural homogeneity. For example, cathodecopper may be induction melted under a charcoal cover or suitable saltflux. High purity or commercial aluminum in the requisite quantity maythen be added and the melt thoroughly stirred to insure adequate mixing.The additional elements may be added in the same manner, that is, highpurity or commercial iron, chromium, titanium, zirconium, molybdenum,columbium, and/ or vanadium may be added in the desired amount and themelt thoroughly stirred to insure adequate mixing. The molten charge maythen be cast by any commercial method which will insure a sound caststructure that is essentially free from entrained aluminum oxide.

The foregoing is, of course, intended to be illustrative and notrestrictive. It is only necessary that there be provided a homogeneous,sound and clean aluminum-bronze alloy satisfying the foregoingcompositional requirements.

The resultant as-cast structure of the alloys of the present inventioncontains a dispersion distributed throughout the alpha, beta matrix asdiscussed above. This dispersion contributes to a finer as-cast grainstructure than the 'binary alloys of the above-identified co-pendingapplication Serial No. 328,184.

As stated above, the alloy is hot worked in the foregoing temperaturerange. The term hot working is employed in its conventional sense,although, in accordance with the present invention hot rolling is thepreferred operation and the present process will be described in moredetail with reference to this preferred mode of operation. Naturally,other methods of hot working will readily suggest themselves to thoseskilled in the art, e.g., forging and extrusion.

The manner of bringing the material into the hot rolling temperaturerange is not critical and any convenient heating rate or method may beemployed.

The temperature of hot rolling is, as stated above, from l850 to 1000F., with it being preferred to utilize a narrower temperature range offrom 1650 F. to 1000 F.

In the process of the present invention, the as-cast material may simplybe heated up to the starting temperature. The time at temperature is notcritical and generally the casting is simply held long enough to insureuniformity of temperature. We then may hot roll directly from thistemperature. During rolling of the ingot, some cooling occurs throughnatural causes. It is not necessary to maintain the ingot at any onestarting temperature. In fact, it is preferred not to maintain the ingotat any one starting temperature, since, as the material cools alphaphase continuously precipitates and the series of reductions atprogressively lower temperatures results progressively in structuralrefinements. In other Words, it is peferred to commence the hot rollingat the more elevated temperatures in the hot rolling temperature rangeand gradually decrease the temperature in order to refine the grainstructure.

The length of time of hot rolling is not critical. The alloy may, ifdesired, be hot rolled until reaching the lower temperature in the hotrolling temperature range, i.e., 1000 F.

It is an advantage of the alloy of the present invention that the hotrolling characteristics thereof are at least as good as those of muchlower strength copper base alloys, such as 70-30 brass, i.e., withrespect to, for example, power consumption and amount of reduction perpass.

Subsequent to hot rolling the alloy contains the maximum amount of alphaphase possible, as governed by the phase equilibrium for the particularcomposition, and in addition a relatively large volume of the previouslydescribed dispersion. The maximum amount of alpha phase is obtained byinsuring that the alloy, either during or subsequent to hot rolling, isheld in the temperature range of 1050 to 1100 F. for at least twominutes. This may be done in a variety of ways either during the hotrolling or by a thermal treatment subsequent thereto. For example, thealloy may be cooled slowly through this temperature range during thenormal course of hot rolling and held there for at least two minutes andpreferably longer.

Subsequent to the hot working step the alloy is cold worked at atemperature of below 500 F., and preferably from 0 to 200 F.

The term cold working is employed in its conventional sense, although,in accordance with the present invention cold rolling is preferred andthe present process will be described in more detail with reference tothis preferred mode of operation. Naturally, other methods of coldworking will readily suggest themselves to those skilled in the art, forexample, drawing, swaging, and cold forging.

As in the above-identified co-pending application Serial No. 328,184, itis especially surprising and unexpected that the alloys of the presentinvention can be readily cold worked, for example, within the optimumcompositional range (9.8 to 10.0 percent aluminum) cold rollingreductions as high as 50 percent are attained, and even higherreductions of over 50 percent aluminum are attained within the broadcompositional range (9.0 to 11.8 percent aluminum) toward the lowaluminum end.

This surprising and unexpected ability permits the introduction of awhole new class of commercial products utilizing thi composition.Particularly important is that these alloys can now be made commerciallyavailable in light gage, coiled strip or sheet form. Such products filla significant commercial need and have heretofore not been availablecommercially.

The particular method of cooling the alloy to cold rolling temperatureis not critical and any convenient method may be employed at anyconvenient cooling rate, for example, the alloy may be spray quenched,cooled in water or air cooled.

The reduction effected during the cold rolling step is dependent uponmany factors. If no additional rolling steps are to be performed, thealloy may be cold rolled to final gage. The exact percentage reductionin the cold rolling is not critical, with the percentage and number ofcold rolling steps dependent upon manufacturing economics. If desired,in order to minimize the cold rolling reduction, the alloy may bereheated within the specified hot rolling range and be further reducedto a smaller thickness for cold rolling.

If desired the alloy may be supplied in this cold rolled form, i.e.,temper rolled.

After the desired reduction has been effected in the cold rolling step,the alloy may be annealed at a temperature of from 1000 F. to 1400 F.,preferably from 1000 F. to 1100 F. and optimally from 1050 F. to 1100 F.As the annealing temperature is increased, the amount of beta phaseincreases and if subsequent cooling does not precipitate the maximumamount of alpha phase, the amount of reduction on subsequent coldrolling is reduced.

The particular method of reheating the alloy to this elevatedtemperature is not especially critical and any convenient heatingprocedure may be employed. The alloy should be held at this elevatedtemperature for at least two minutes.

In the preferred embodiment the cold rolling and annealing steps arerepeated, preferably a plurality of times. Optimum results have beenfound at three cycles of cold rolling and annealing. The practice of thepresent invention, and in particular the three cycles of cold rollingand annealing, effectively develops a fine grained structure. It is thisfine grained structure that results in the attainment of a superiorcombination of strength and ductility in these alloys. If desired thealloy may be supplied in the as-annealed condition also having a finegrain size. This form provides the maximum formability.

The process of the present invention is extremely versatile and a greatmany variations will readily suggest themselves to those skilled in theart. For example, the alloy may be heat treated after cold rolling at1100 F. to 1800 F. followed by rapid cooling. The temperature of heattreating varies inversely in relation to the aluminum content, i.e., thelower the aluminum content the higher the temperature of the heattreatment. For the composition containing the optimum amount ofaluminum, the heat treatment temperature is 1500 F. to 1650 F. The timeat temperature is immaterial, it

being necessary only to allow sufficient time to insure uniformity oftemperature. After heat treatment the alloy is rapidly cooled below atleast 1000 F.; thereafter, the rate of cooling is not critical. Thepreferred mode of cooling is to cool in water, however, the alloy mayalso be oil quenched or cooled in circulating air.

The heat treatment converts most of the alloy to the beta phase. In therapid cooling, the alloy retains a high proportion of beta phase and thebeta phase undergoes a structural transformation known as a martensitictransformation which results in a significant increase in strength andresults in an alloy having an excellent combination of strength andductility. Thus, this combination of heat treatment and rapid coolingwill be termed a betatizing procedure.

The dispersion present in the micro-structure of the present alloy actsto effectively inhibit grain growth during betatizing and therebycontributes to a finer final grain size. This is an importantdistinction between the present alloys and the alloys of co-pendingapplication Serial No. 328,184, since the finer grain size contributesto the improved properties of the present alloys.

In the rapid cooling, it is necessary only that the alloy be cooledrapidly at least to below 1000 F., i.e., to at least below the eutectoidtransformation temperature, although the alloy may be rapidly cooled toa lower temperature if desired.

Still greater improvements may be attained by a tempering procedurefollowing betatizing. This results in still better strength, principallyyield strength. It is accomplished by holding the alloy for at least 30minutes at a temperature of from 500 F. to 900 F. and preferably from600 to 750 F. Still further improvements in strength may be had by coldrolling either prior to or subsequent to tempering.

Upon tempering, the present alloys develop higher strength levels thanthose of co-pending application Serial No. 328,184 and also gain greaterstrength during tempering. 'It is believed that this increased gain instrength is due to precipitation hardening effects superimposed upon thenormal tempering effects. It is further believed that the precipitationhardening is associated with the precipitation from supersaturated solidsolution of the intermetallic compounds referred to above. 1

Another modification of the present invention is to form the annealedalloy into component shapes taking advantage of its excellentformability. The alloy is then heat treated in the formed shape to highstength levels. This is particularly useful in, for example, bellows anddiaphragms.

Another modification is to form the annealed or temper rolled alloy intothe desired shape. The formed part is then joined by such a treatment asbrazing at 1400 F. to 1700 F., during which treatment the part isautomatically converted to a high proportion of beta phase and ifsubsequently rapidly quenched very high strength levels are developed,i.e., betatizing. The presence of the dispersion in the present alloyshas the same advantageous effects discussed above.

Alternatively, subsequent to the brazing or heat treatment in the formedshape, further strength increases may be attained due to tempering, withthe dispersion having the same beneficial effects discussed above. Thismay be accomplished by any subsequent treatment either by specialthermal treatment or by. additional joining, e.g., soldering, which iscarried out in the tempering range.

As will be apparent, the process of the present invention isexceptionally versatile and numerous other modifications will readilysuggest themselves to one skilled in the art within the spirit of thepresent invention.

In accordance with the present invention it has been found that thesimple and convenient process discussed above results in a new andimproved aluminum-bronze alloy possessing highly desirable, and in factsurprising,

physical properties heretofore unattainable in alloys of this type.

The alloy contains from 9.0 to 11.8 percent aluminum, from 0.05 to 5.0percent of at least one additional element as defined above, and thebalance essentially copper. In addition, the alloy has metallographicstructure containing from to 95 percent beta phase and the remainderalpha phase, preferably 85 to 95 percent beta phase. In addition, thealloy contains a dispersion, as discussed above. The alloy has auniformly fine metallographic grain structure with a particle size lessthan 0.065 mm., and generally less than 0.040 mm.

The alloys of the present invention possess properties which areunexpected and surprising in alloys of this type, especially with regardto strength and ductility. For example, tensile strengths ranging from120,000 to 160,- 000 p.s.i. and yield strengths from 60,000 to 80,000p.s.i. (0.2 percent otfset) may be developed in combination withelongations ranging from 12 to 9 percent. The electrical conductivitiesare good for alloys of this type, ranging from 10 to 16 percent IACS. Inaddition, modifications of the present invention improve the propertiesstill further. For example, tempering increases the yield strengthconsiderably, e.g., to from 60,000 to 11,000 p.s.i., at the expense,however, of ductility. In another modification consisting of coldrolling the alloy following an annealing operation, yield strengthvalues as high as 115,000 p.s.i. and higher may be achieved togetherwith tensile strengths as high as 148,000 p.s.i.

Still further, these properties are obtained with retention of the otherdesirable properties in alloys of this type, for example goodbrazability, solderability, weldability, corrosion resistance, stresscorrosion resistance, and fatigue strength.

The present invention and improvements resulting therefrom will be morereadily apparent from a consideration of the following illustrativeexamples.

Example 1 (A .-C0pper-Aluminum-Iron Alloys Alloys having the followingcompositions were prepared from a charge of cathode copper,aluminum-iron master alloy and commercial purity aluminum in the form of1%" x 1%" x 4 /2" chill castings.

. Al9.4%, Fe-5.0%, Cuessentially balance Al9.8%, Fe3.0%, Cuessentiallybalance Al10.0%, Fe4.0%, Cu-essentially balance Al-l0.0%, P e-1.8%,Cuessentially balance Al10.0%, Fe5.0%, Cuessentially balance \Each ofthe alloys were hot rolled in the temperature range of from 1600 to 1300F. Reductions of about 10 to 20 percent per pass were used in reducingthe gage from 1.75" to 0.050". These reductions were limited primarilyby the roll diameter, with greater reductions readily obtainableespecially on alloys containing 10% or more aluminum having all betastructures at 1600 F. and, therefore, exhibiting maximum hotrollability.

Example I(B) Following hot rolling all of the alloys of Example I(A)were betatized at 1150 F. for minutes and subsequently air cooled formaximum cold rollability. In the low temperature, betatized conditionthe above alloy containing 10.0% Al and 5.0% Fe, for example, could becold rolled The microstructures of all of the alloys were then furtherrefined by cold rolling from 0.050" to 0.025". This was accomplished inthree steps with intermediate annealing at 1150 F. after each cold roll.A grain size of about 0.010 mm. in diameter was developed in the alloysby this cold reduction.

The microstructures of the alloys contained a discrete, uniformlydistributed dispersion rich in the additional element iron.

8 Example I (C) Maximum tensile properties were developed in the alloysafter the treatment of Example I(B) by betatizing in the range of 1500to 1750" F. to produce about beta phase and 5% alpha phase. For the 10%Al5.0% Fe alloy, maximum properties were obtained by betatizing at 1550F. for 30 minutes followed by water quenching to give:

Yield strength p.s.i 56,600 Tensile strength p.s.i 165,100 Elongationpercent 10.0

Further improvement in yield strength was accomplished by betatizing at1570 F. and tempering at 650 F. for one hour to give:

Yield strength p.s.i. 101,500 Tensile strength p.s.i 165,000 Elongation"percent-.. 5.0

Electrical conductivity of the 10% Al5.0% Fe alloy was 10.3% IACSbetatized at 1500 F. followed by water quench. Improvement inconductivity was obtained by subsequent tempering at 650 F. for onehour. The electrical conductivity increased to 11.4% IACS.

Similar properties were obtained in the other alloys by achieving acomparable proportion of alpha and beta phase by suitable adjustment ofthe betatizing temperature.

Example II(A).C0pper-aluminum-ir0n alloys Alloys having the followingcompositions were prepared from a similar charge as in Example I(A) inthe form of 2 /2" x 12" x 30" D.C. castings.

1. Al9.2% Fe-4.4% Cuessentially balance 2. Al9.3 Fe4.3 Cuessentiallybalance 3. Al9.5 Fe4.9%, Cuessentially balance 4. Ail-10.1%, Crl.06%,Cuessentially balance The alloys were hot rolled in the temperaturerange of from 1600 to 1300 F. Reductions of about 5 to 10 percent perpass were used in reducing the gage from 2.5" to 0.35", with thereductions being limited by the roll diameter as in Example I(A).

Example II(B) Yield strength p.s.i 50,000 Tensile strength p.s.i 96,000Elongation "percent" 33 Cold rolling this alloy 54% gave the followingproperties:

Yield strength p.s.i 115,800 Tensile strength p.s.i 148,000 Elongationpercent 2.0

Similar properties were developed in the other alloys.

Example II(C) Maximum tensile properties were developed in the alloys ofExample II(B) by betatizing to produce maximum beta phase in a mannerafter Example I(C) For example, the alloy containing 9.5 A1 and 4.9% Fewas betatized at 1628 F. for 30 minutes followed by water quenching. Asa result of this treatment this alloy exhibited:

Yield strength p s 1' 64,000 Tensile strength p s 1' 161,000 Elongationpercent 7 Yield strength p.s.i 106,200 Tensile strength p s i 168,000Elongation percent 5.0

Similar properties were developed in the other alloys of Example lI(B).

Example III(A).-Cpper-alummum-chromium alloys Alloys having thefollowing compositions were prepared from a charge of cathode copper,aluminum-chromium master alloy and commercial purity aluminum in theform of 1% x 1%" x 4 /2" chill castings.

l. Al9.'7%, Crl.2%, Cuessentially balance 2. Al-9.9%, Cr--0.46%,Cu-essentially balance 3. All0.0%, Cr1.04%, Cu-essentially balance 4.Al10.1%, Cr1.06%, Cu-essentially balance Each of the alloys were hotrolled in the temperature range of from 1600 to 1300" F. Reductions ofabout 10 to 20 percent per pass were used in reducing the gage from 1.75to 0.050, with reductions being limited by the roll diameter.

Example 111(B) Example 1II(C) Maximum tensile properties were developedin all the alloys in a manner after Example I(C) by betatizing toproduce maximum beta phase. For example, the alloy containing 10.1% Aland 1.06% Cr was betatized at 1550 F. for 30 minutes followed by waterquenching to give:

Yield strength p.s.i 67,000 Tensile strength p.s.i 162,800 Elongationpercent 10 Further improvement in yield strength was accomplished bybetatizing at 1570 F. for 30 minutes followed by tempering at 650 F. forone hour to give:

Yield strength p.s.i. 111,700 Tensile strength p s 1' 169,200 Elongationpercent 5 Electrical conductivity of this alloy was 12.5% IACS betatizedat 1500 F. followed by water quench. Improvement in conductivity wasobtained by subsequent tempering at 650 F, for one hour. The electricalconductivity increased to 15.1% LACS.

Similar properties were developed in the other alloys by achieving acomparable proportion of alpha and beta phase by suitable adjustment ofthe betatizing tempera ture.

Example I V(A).C0pper-alummum-zirconium alloys Alloys having thefollowing compositions were prepared as in Example I(A) in the form of1%" x 1% x 4 /2" chill castings.

1. Al-9.9% Zr-0.l7%, Cuessentially balance 2. Al10.0%, Zr0.24%,Cuessentially balance 3. Al--10.1%, Zr0.08%, Cuessentially balance Eachof the alloys were hot rolled in a manner after Example I(A).

Example IV(B) Following hot rolling all of the alloys of Example IV(A)were betatized in a manner after Example I(B) at 1150 F. for 30 minutesand subsequently air cooled for maximum cold rollability. In the lowtemperature, betatized condition the above alloy containing 9.9% A1 and0.17% Zr, for example, could be cold rolled 50 percent.

The microstructures of all of the alloys were then further refined bycold rolling as in Example I(B) to develop a grain size of about 0.010mm. in diameter. The microstructures of the alloys contained a discrete,uniformly distributed dispersion rich in zirconium.

Example IV(C) Maximum tensile properties were developed in all of thealloys of Example IV(B) by betatizing in a manner after Example I(C) toproduce about beta phase and 5% alpha phase. For example, in the abovealloy contaning 10.1% Al and 0.08% Zr, maximum properties were obtainedby betatizing at 1550 F. for 30 minutes followed by Water quenching togive:

Yield strength p.s.i 82,600 Tensile strength p.s.i 143,000 Elongationpercent Further improvement in yield strength was obtained by betatizingat 1570 F. for 30 minutes followed by a water quench and tempering at650 F. for one hour to give:

Yield strengt p.s.i 115,600 Tensile strength p.s.i 152,200 Elongationpercent 2 Electrical conductivity of this alloy was 12.4% IACS betatizedat 1500 F. followed by water quench. Improvement in conductivity wasobtained by subsequent tempering at 650 F. for one hour to give a valueof 13.7% IACS.

Similar properties were developed in the other alloys by achieving acomparable proportion of alpha and beta phase by suitable adjustment ofthe betatizing temperature.

Example V( A .C 0p per-a l umin um-titaizium alloys Alloys having thefollowing compositions were prepared as in Example I(A) in the form of1%" x 1%" X 4 /2 chill castings, except that the charcoal cover wasremoved and a KCl flux cover was used when the aluminum-titanium masteralloy was added.

1. Al10.3 Ti2.0% Cu-essentially balance 2. Al-11.4%, Ti1.1%,Cu-essentially balance 3. All 1.6%, Ti--1.2%, Cu-essentially balanceEach of the alloys were hot rolled in a manner after Example I(A).

Example V(B) Following hot rolling all of the alloys of Example V(A)microstructures of the alloys contained a discrete, uniformlydistributed dispersion rich in titanium.

xample V(C) Maximum tensile properties were developed in all of thealloys of Example V(B) by betatizing in a manner after Example I(C) toproduce about 95% beta phase and 5% alpha phase. For example, in theabove alloy containing 10.3% Al and 2.0% Ti, maximum properties wereobtained by betatizing at 1550 F. for 30 minutes followed by waterquenching to give:

Yield strength p.s.i 93,600 Tensile strength p.s.i 143,200 Elongationpercent 3 Tempering caused a slight increase in yield strength but areduction in tensile strength. Electrical conductivity of this alloy was10.8% IACS betatized at 1500 F. followed by water quench. Improvement inconductivity was obtained by subsequent tempering at 650 F. for one hourto give a value of 13.2% IACS.

Similar properties were developed in the other alloys by achieving acomparable proportion of alpha and beta phase by suitable adjustment ofthe betatizing temperature.

Example VI.Cmparative Alloys containing 9.0, 10.0, 10.3, 10.5 and 11.1percent aluminum and the balance essentially copper were made from acharge of cathode copper and commercial purity aluminum in the form of1%" x 1%" x 4 /2 chill castings.

The alloys were hot rolled in the temperature range of from 1600 to 1300F. Reductions of about 10 to 20 percent per pass were used in reducingthe gage from 1.75 to 0.1.

Following hot rolling, the alloys were betatized at 1100 F. for 30minutes and subsequently air cooled for maximum cold rollability.

The microstructures of the alloys were further refined by cold rollingin three steps with intermediate annealing at 1100 F. after each coldroll. The gage was reduced from 0.100" to 0.050". As a result of thiscold rolling with inter anneals at 1100 F., grain sizes of about 0.020mm. in diameter were obtained for each of the above alloys. There was nodiscrete dispersion, as in the previous examples.

Maximum tensile properties were developed in the alloys by betatizing atsuitably high temperatures to produce about 95 percent beta phase and 5percent alpha phase. For the percent aluminum alloy, maximum propertieswere obtained by betatizing at 1525 F. for 30 minutes followed by waterquenching. As a result of this treatment, the 10 percent aluminum alloyexhibited a yield strength of 53,800 p.s.i., a tensile strength of125,000 p.s.i. and 8.5 percent elongation. Further improvement instrength was accomplished by tempering at 650 F. for one hour. The yieldstrength of the 10 percent aluminum alloy was increased to 127,000p.s.i. with a corresponding reduction in elongation to 1.5 percent.

Similar properties were obtained in the other alloys by achieving acomparable proportion of alpha and beta phase by suitable adjustment ofthe betatizing temperature.

Example VII.-Comparative An alloy was cast in a manner after Example Icontaining 9.4 percent aluminum and the balance essentially copper. Thealloy was hot worked by extrusion and then drawn into a final plateform. The resultant alloy had a tensile strength of 75,000 p.s.i., ayield strength of 35,000 p.s.i. and an elongation of 28 percent.

The maximum properties that were developed by betatizing at 1600 F. andwater quenching were only 109,000 p.s.i. tensile strength, 28,000 p.s.i.yield strength and 29 percent elongation owing to a comparatively coarsegrained structure, none of the grains being under 0.065 mm. in diameter.

The response of this material to tempering increased the yield strengthonly a small amount to about 35,000 p.s.i.

Example VIII.Comparative In a manner after Example I, an alloycontaining 12.0 percent aluminum and the balance essentially copper washot rolled, betatized and cold rolled. Cold rolling was extremelydiflicult and at reduction of about 5 percent the alloy fragmentedbeyond further use.

Example IX.C0mparative An alloy containing 8 percent aluminum and thebalance essentially copper was treated in a manner after Example I. Theproperties attained were: 140,000 p.s.i. tensile strength; and 65,000p.s.i. yield strength. Further heat treatment did not result in furtherimprovement.

As pointed out heretofore, both the alloys of the present invention andthe alloys of co-pending application S.N. 328,184 are extremelyversatile and susceptible of a great many uses. For example, in unfiredcryogenic pressure vessels wherein exceptionally high weld strengths canbe developed. When an alloy in the softened condition, i.e., maximumalpha, is TIG welded using the parent metal as filler, the tensilefailures always occur in the base plate. Thus, the properties of theweldrnent are easentially those of the base material.

Other uses of the present alloys and those of the above co-pendingapplication include uses similar to berylliumcopper where high strengthand non-sparking is required. Also in cutlery where exceptionally highlevels of hardening and cutting ability are obtained by combination ofheat treatment and cold rolling. In this application, a high corrosionresistance material will preserve the cutting edge for long periods. Inaddition, the alloys may be used as Wire alloys in Fourdrinier machinesdue to their high strength and corrosion resistance, providing superiorperformance than copper base alloys conventionally used. A further useis as a bearing material in steel backed bearings because of amulti-cornponent structure in which a hard phase can be distributedthrough a soft matrix.

This invention may be embodied in other form or carried out in otherways without departing from the spirit or essential characteristicsthereof. The present embodiment is therefore to be considered as in allrespects illustrative and not restrictive; the scope of the inventionbeing indicated by the appended claims, and all changes which comewithin the meaning and range of equivalency are intended to be embracedtherein.

What is claimed is:

1. A high strength cold rolled and heat treated aluminum-bronze alloyhaving a minimum tensile strength of 120,000 p.s.i., a minimum yieldstrength of 60,000 p.s.i. at 0.2 percent offset consisting essentiallyof (A) from 9.0 to 11.8 percent aluminum; (B) from 0.05 to 5.0 percentof at least one additional element having a solid solubility in copperof less than 4.0 percent and which forms at least one intermetalliccompound with aluminum, with the total quantity of said additionalelements being less than 10.0 percent; and (C) the balance essentiallycopper, said alloy having a metallographic structure containing from 5to 95 percent beta phase, wherein the beta phase has a martensiticstructure, and remainder alpha phase and having a uniformly finemetallographic grain structure with a grain size less than 0.065 mm.,said alloy containing a discrete, uniformly distributed dispersion richin said additional element.

2. An alloy according to claim 1 containing from to percent beta phase.

3. An alloy according to claim 1 with the total quantity of saidadditional elements being less than 5 percent.

4. An alloy according to claim 1 wherein said additional element isselected from the group consisting of cent.

6. An alloy according to claim 4 wherein said additional element ischromium in an amount of from 0.4 to

2.0 percent.

7. An alloy according to claim 4 wherein said additional element istitanium in an amount of from 0.4 to

2.0 percent.

8. An alloy according to claim 4 wherein said additional element iszirconium in an amount of from 0.05 to 0.2 percent.

References Cited by the Examiner UNITED STATES PATENTS Richardson14811.5

Klement 75162 X Klement 75162 Klement 75162 10 HYLAND BIZOT, PrimaryExaminer.

DAVID L. RECK, Examiner. H. F. SAITO, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 3 297,497 January 10 1967 George H. Eichelman, Jr., et a1.

It is hereby certified that error appears in the above numbered patentrequiring correction and that the said Letters Patent should read ascorrected below.

Column 1, line 43, for "cost of" read cost column 8, line 39, for"Al-10.1%, (Ir-1.06%" read Al-9.6%, e-4.3%

Signed and sealed this 15th day of October 1968.

(SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

1. A HIGH STRENGTH COLD ROLLED AND HEAT TREATED ALUMINUM-BRONZE ALLOYHAVING A MINIMUM TENSILE STRENGTH OF 120,000 P.S.I., A MINIMUM YIELDSTRENGTH OF 60,000 P.S.I. AT 0.2 PERCENT OFFSET CONSISTING ESSENTIALLYOF (A) FROM 9.0 TO 11.8 PERCENT ALUMINUM; (B) FROM 0.05 PERCENT OF ATLEAST ONE ADDITIONAL ELEMENT HAVING A SOLID SOLUBILITY IN COPPER OF LESSTHAN 4.0 PERCENT AND WHICH FORMS AT LEAST ONE INTERMETALLIC COMPOUNDWITH ALUMINUM, WITH THE TOTAL QUANTITY OF SAID ADDITIONAL ELEMENTS BEINGLESS THAN 10.0 PERCENT; AND (C) THE BALANCE ESSENTIALLY COPPER, SAIDALLOY HAVING A METALLOGRAPHIC STRUCTURE CONTAINING FROM 5 TO 95 PERCENTBETA PHASE, WHEREIN THE BETA PHASE HAS A MARTENSITIC STRUCTURE, ANDREMAINDER ALPHA PHASE AND HAVING A UNIFORMLY FINE METALLOGRAPHIC GRAINSTRUCTURE WITH GRAIN SIZE LESS THAN 0.065 MM., SAID ALLOY CONTAINING ADISCRETE, UNIFORMLY DISTRIBUTED DISPERSION RICH IN SAID ADDITIONALELEMENT.